1. Technical Field
The present invention is directed to a metal-enhanced detection system and method for increasing sensitivity and rapidity of the detection system, and more particularly, using sonication in combination with metallic enhanced, fluorescence or chemiluminescence detection assays to increase the speed and sensitivity of the detection system.
2. Background of Related Art
The identification and quantification of proteins and other biomolecules using bioassays are of great importance in biomedical and biochemical applications.1-3 Fluorescence is the dominant technology in most of these applications, where a biomolecule of interest is detected by fluorescence emission from its fluorophore labeled binding partner.4, 5 Fluorescence-based bioassays those carried out on planar surfaces generally lack sensitivity and require expensive optical instruments.6, 7 In addition, the biorecognition events in these assays are inherently slow (several minutes to hours).6, 7 The sensitivity of the fluorescence-based assays can be improved, without the use of high-end optical instruments, by incorporating plasmon resonant particles (PSPs) into these assays.8, 9 The improved sensitivity is made possible by the increase in fluorescence signatures and decreased lifetimes of fluorophores placed in close proximity to PSPs, described by a phenomenon called Metal-Enhanced Fluorescence (MEF).8, 10 In MEF-based bioassays, PSPs (generally silver nanoparticles) are deposited onto the planar surface and the bioassay is constructed on the PSPs.8 Since the size of most biomolecules are smaller than PSPs (20-100 nm), fluorophores are positioned within a distance where their emission is increased due to their interactions with the surface plasmons of PSPs.10 
Although the sensitivity of fluorescence-based bioassays is addressed by MEF, the speed of the bioassays remains a huge challenge to overcome. In this regard, a new technique, called Microwave-Accelerated Metal-Enhanced Fluorescence (MAMEF)11 that amalgamates low power microwave heating and MEF was shown to decrease the bioassay completion times to less than 1 min. In MAMEF, low power heating of the assay components creates a temperature gradient between the bulk (target biomolecules and fluorescent probes are present) and the silver nanoparticles at the assay surface (capture probe is present), which drives the target biomolecules and fluorescent probes towards the surface and the bioassay is constructed.11 The microwave heating step can be carried out separately for each assay component or in one step for a 3-piece DNA hybridization assay.12 However, several factors affect the efficiency of the MAMEF technique: 1) assay surfaces have to be modified to remove excess heating (especially in assays run with small volume of liquid),11 2) the heating of large assay platforms with multiple sharp corners13 (e.g., High Throughput Screening Wells) require longer heating times that subsequently lead to the evaporation of sample.
In surface plasmon-coupled chemiluminescence (SPCC), where the luminescence from chemically induced electronic excited states couples to surface plasmons in metalized particles or surfaces, the kinetics of the systems relies on chemically induced electronically excited states that occur without an external excitation source. However, in chemiluminescence systems, detection is limited by the quantum efficiency of the chemiluminescence reaction or probe, and the time before depletion of the reactants. Thus, it would be beneficial to increase the movement of the reactants to increase the speed of the chemiluminescence reaction.
In this regard, there is still a need for a more generic technique applicable to all commercially available assay platforms without the sacrifice of samples.